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We all know a good night's sleep is an integral part of a healthy lifestyle. Going to bed and getting a full seven to eight hours benefits our heart, weight, mind, and even fertility. Researchers at Harbin Medical University in China found late bedtimes and sleeping less can destroy healthy sperm; a possible cause for infertility.

"Sperm counts and their survival rates were lower in the short sleepers as compared to others within each group," wrote the researchers, in the abstract.

Specifically, sleeping for six hours or less led to lower sperm counts in men, with sperm dying much faster than in the other groups. Previous research has confirmed men who get six hours of sleep a night had sperm counts 25 percent lower than men sleeping for a full eight hours. This prompted Chinese researchers to explore how sleep duration and bedtime would impact sperm health, and what mechanisms in the body could be triggering these changes.

In the new study, published in Medical Science Monitor, 980 healthy Chinese men were divided into three different bedtime groups: between 8 p.m. and 10 p.m., between 10 p.m. and midnight, or after midnight. The participants' alarms were set so they'd get six hours of sleep or less, seven to eight hours, or nine hours or more. The researchers took regular semen samples from the men to examine sperm shape, count, survival, and motility according to sleep patterns.

The findings revealed sperm counts and their survival rates were lower in those who went to bed late and got little sleep. Similarly, sleeping for more than nine hours had the same effect on sperm quality as did getting six hours or less at night. The researchers suspect late bedtimes and little sleep trigger the increase of anti-sperm antibody, a protein produced by the immune system, which can destroy healthy sperm.

Researchers find going to sleep after midnight can affect men's sperm health, and overall fertility.Photo courtesy of Pixabay, Public Domain

Anti-sperm antibodies act by blocking sperm movement, capacitation fertilization, and inhibit embryo implantation. It's believed that its presence in semen and serum are among the causes of immune infertility. In other words, the bodies of people with immunological fertility problems identify part of the reproductive function as an enemy and send “natural killer” (NK) cells to attack.

Therefore, men with high numbers of sperm antibodies make it difficult for their sperm to reach the egg, and/or fertilize the egg, possibly leading to infertility. Anti-sperm antibodies can damage sperm that do survive, and this could lead to a miscarriage. In men, the testicles protect the sperm from immune cells, but when they are damaged, they may no longer be able to do that.

Testosterone is necessary for reproduction, and the majority of daily testosterone release in men occurs during sleep. In the research, men who had trouble sleeping more than half the time they were trying to conceive — no more than six menstrual cycles — were also less likely to impregnate their partner than those who didn't.

Currently, there is still limited data about how men's sleeping patterns influence fertility. However, a common finding is men should aim for seven to less than nine hours of sleep to optimize their fertility and boost their chances of becoming a dad. When it comes to women and sleep, the science remains unknown.

Bottom line: getting too little or too much sleep can be detrimental to our sex life, especially if we’re trying add a plus one to our family.